Dermatologic Surgery

What are the 3 layers of skin?

Epidermis: outermost avascular layer, 90% keratinocytes; also houses melanocytes and Langerhans cells

Dermis: connective tissue (collagen/elastin), vessels, lymphatics, nerves and adnexa; gives tensile strength

Hypodermis (subcutis): adipose + loose connective tissue; insulation, cushioning, energy storage

What are the 4 epidermal strata from bottom to top?

Basale -> spinosum -> granulosum -> corneum (for palms/soles add stratum lucidum)

Describe the stratum basale

Proliferating keratinocyte stem cells; melanocytes reside here (origin of melanoma)

Describe straum corneum

Anucleate corneocytes + lipids = waterproof barrier

Describe the dermis

Papillary (superficial, capillary-rich) and reticular (deepn, dense collagen) layers.

How does barrier loss (burns, wounds) correlate clinically?

Fluid/heat loss and infection risk

How does depth of a lesion correlate clinically?

Determines biopsy choice and defines excision depth (to fascia for invasive melanoma)

How does dermal vascular plexuses correlate clinically?

Govern flap viability and graft "take"

How does adnexal structures (pilosebaceous unit, apocrine glands) correlate clinically?

Origin of cysts and hidradenitis suppurativa

What is the #1 most common cancer in the world?

Skin cancer

What are the 4 types of skin cancer?

1. Basal cell carcinoma (BCC, most common),

2. Squamous cell carcinoma (SCC),

3. Melanoma,

4. Merkel cell carcinoma

What are the exposure risks for skin cancer?

1. UV light,

2. Sunburns,

3. Tanning beds,

4. Chemicals,

5. Radiation

What are the patient risk factors for skin cancer?

1. Skin type - Fitzpatrick grading,

2. Xeroderma pigmentosum,

3. Family history

What is the most common complaint with a melanoma?

A new, changing or irregularly pigmented lesion.

54% of people report a change in the lesion, 6% report bleeding/ulceration and 3% report pruritus.

What distinguishes melanoma from benign lesions?

Rapid growth within 6 weeks/ atypical lesion de novo.

What are the risk factors for melanoma?

UV/indoor tanning, fair skin that burns, blistering sunburns, many or atypical nevi, personal/family history

What are the ABCDEs of melanoma?

A: asymmetry, halves don't match

B: border, irregular, ragged, poorly defined

C: color, variegated: tan/brown/black +/- red, white, blue

D: diameter, >6mm (pencil eraser)

E: evolving, change in size, shape or color over time.

What should be added to ABCDE for nodular melanoma?

EFG: Elevated, firm, growing.

Nodular lesions can lack classic ABCDE features.

What exam components should be done for melanoma beyond ABCDE?

1. Ugly duckling sign

2. Full skin exam

3. Dermoscopy

4. Amelanotic melanoma: pink/red/skin-colored

5. Subungual: longitudinal pigmented band +/- Hutchinson sign (periungual spread)

Describe superficial spreading melanoma

Approx. prevalence: ~70%

Hallmark features: trunk/extremities, younger adults; intermittent sun; BRAF V600E common

Describe lentigo maligna melanoma

Approx. prevalence: ~15%

Hallmark features: head/neck of older adults; chronic sun damage/solar elastosis (stage 0 resemble "sun spots")

Describe nodular melanoma

Approx. prevalence: ~5-10%

Hallmark features: rapidly growing, vertical growth; firm dome-shaped nodule; disproportionate mortality (high risk)

Describe acral lentiginous melanoma

Approx. prevalence: ~1-3%

Hallmark features: palms/soles, subungual; most common subtype in darker skin tones

What is the prevalence of cutaneous melanoma?

94% of all melanoma is cutaneous melanoma.

What is the preferred method for a skin biopsy of a suspicious pigmented lesion?

Excisional/complete biopsy with 1-3mm margins, full thickness to avoid transecting the base. Then plan definitive wide excision.

What are the techniques for a skin biopsy for a suspicious pigmented lesion?

Elliptical/fusiform excision, punch (small lesions) or deep shave/saucerization below the lesion plane.

Why should you avoid wider margins in a skin biopsy for a suspicious pigmented lesion?

It preserves accurate lymphatic mapping for later SLNB (sentinel lymph node biopsy)

Orient elliptical biopsies to anticipate definitive wide excision (longitudinal on extremities)

What is the difference between a punch biopsy and a shave biopsy?

Punch: full-thickness core with a punch tool, good for small lesions

Shave: tangential removal; deep shave/saucerization goes below the lesion plan.

When should you use excisional biopsy vs shave/punch?

If you suspect melanoma, excisional is preferred. Use shave and punch biopsies for lesions that are not suspicious for melanoma.

When is partial (incisional) biopsy accetable?

1. Constrained sites: acceptable for facial or acral sites, very large lesions, or low suspicion,

2. Sample the worst area: full thickness incisional/punch of the thickest or most atypical area is acceptable in constrained sites,

3. Nail matrix biopsy: for suspected subungual melanoma (requires expertise),

What is the risk with partial biopsy?

Risk of understaging. Partial sampling can understage - repeat narrow excisional biopsy if inadequate, unless criteria for SLNB are already met.

What is melanoma treatment based on?

TNM

Tumor

Nodes

Metastasis

Mitotic rate is also considered

What are the treatment options for melanoma?

Surgical: wide local excision - margins based on TNM and Breslow depth

Sentinel lymph node biopsy

Nonsurgical: immunotherapy

Lifetime surveillance

NO Mohs surgery

What is done for melanoma with Breslow thickness of: in situ?

Recommended peripheral margin: 0.5- 1 cm (≥0.5cm)

What is done for melanoma with Breslow thickness of: ≤1.0mm

Recommended peripheral margin: 1 cm (category 1)

What is done for melanoma with Breslow thickness of: >1.0-2.0mm?

Recommended peripheral margin: 1-2 cm (category 1)

What is done for melanoma with Breslow thickness of: >2.0-4.0mm?

Recommended peripheral margin: 2 cm (category 1)

What is done for melanoma with Breslow thickness of: >4.0mm?

Recommended peripheral margin: 2 cm (category 1)

How does depth of excision impact treatment?

Invasive: down to (not including) muscular fascia

In situ: skin + superficial subcutaneous fat

Lentigo maligna: may need >0.5 cm (subclinical extension)

SLNB: consider if ulcerated or ≥0.8 mm

What is the method for a SLNB?

Used to find the first draining lymph nodes

Inject isosulfan blue dye and/or radioactive isotope around the melanoma - dual tracer >95% accurate

Evaluated via a separate incision

Consider for ulcerated or ≥0.8 mm tumors.

How do you diagnose basal cell carcinoma?

Shave or punch biopsy

What are the nonsurgical treatments for BCC?

1. Cryotherapy,

2. Electrodesiccation and curettage,

3. Topical preparations,

4. Immunotherapy,

5. Radiation

Lifetime surveillance for every patient

What are the surgical treatments for BCC?

1. Wide local excision,

2. Mohs surgery

Lifetime surveillance for every patient

What is the method for Mohs micrographic surgery?

Tissue removed in layers; complete margin assessment on mapped histologic sections

Repeat layers only where tumor remains - tissue sparing

Gold standard for high risk facial BCC/SCC

NOT used fro primary invasive melanoma

How do you diagnose and treat SCC?

Diagnosis: shave/punch biopsy

Non-surgical treatment: same as BCC

Surgical treatment: wide local excision, Mohs surgery, lymph node evaluation required

Lifetime surveillance for every patient

What are the margins for BCC?

4-5 mm. Clinical margin for small, well-defined lesions; most common skin cancer.

What are the margins for cutaneous SCC?

4 mm and 10 mm. 4 mm for tumors

What are the margins for Mohs?

Complete margins, gold standard for high risk facial BCC/SCC; tissue-sparing.

Is Mohs recommended for melanoma?

It is not recommended when standard margins are achievable.

What is the presentation of a soft-tissue sarcoma?

Painless, enlarging soft-tissue mass; later comprehensive symptoms/functional impairment.

Deep-seated (below fascia) tumors behave more aggressively than superficial ones.

1% of adult malignancies

What are the red flags for a mass?

1. Size >5 cm,

2. Deep to fascia,

3. Rapidly growing,

4. Recurrent

Where are most soft-tissue sarcomas?

43-60% on extremities.

Where do different subtypes of soft-tissue sarcomas occur?

Leiomyosarcoma: retroperitoneum/abdomen

Liposarcoma and UPS: thigh

Synovial/epithelioid/clear cell: upper limb

What are the most common soft-tissue sarcoma subtypes in adults?

Liposarcoma: 20%

Leiomyosarcoma: 15%

Undiff. pleomorphic sarcoma: 10-15%

What are the age patterns with soft-tissue sarcomas?

Children: rhabdomyosarcoma

Young adults: synovial sarcoma

Older adults: LMS/LPS/UPS

What are the surgical principles for soft-tissue sarcoma?

1. Biopsy first: percutaneous core needle biopsy preferred,

2. Wide resection: oncologically appropriate wide resection with negative margins is the goal,

3. Limb-sparing: standard of care, amputation is reserved for preference or when resection would leave the limb nonfunctional,

4. Respect planes: dissec through normal tissue planes

What is an epidermal inclusion cyst?

Most common cutaneous cyst; keratin-filled, stratified squamous epithelial wall; face/neck/trunk

Dx clinical: firm, mobile nodule with central punctum

Can become inflated, infected or rupture

Inflamed lesion: intralesional steroid, then interval excision.

Treatment: complete surgical excision including the cyst wall, prevents recurrence; drainage alone recurs.

What is a lipoma?

Soft, mobile, nontender subcutaneous mass; most common benign soft-tissue mass

Dx usually clinical; slow-growing and painless

Treatment: excision/manual expression when symptomatic or for cosmesis

When should you image or biopsy any lesion?

If it is:

- Large (>5 cm)

- Deep to fascia

- Rapidly growing

- Fixed

What are other common benign skin tumors and their treatments?

1. Acrochordon (skin tags): snip/shave excision, cryo, electrodesiccation

2. Cherry angioma: laser, cryo, electro

3. Dermatofibroma: treat only if symptomatic

4. Keloid: intralesional steroid

5. Keratoacanthoma: excise, hard to distinguish from SCC

What is cellulitis?

Acute bacterial infection of dermis and subcutaneous tissue; most commonly strep and S. aureus.

Clinical features: expanding erythema, warmth, edema, tenderness +/- fever.

Purulent: cover MRSA

Nonpurulent: cover strep

Mark borders, elevate limb; failure to improve reassess for abscess, resistant organisms or nec. infection.

What is the definitive treatment for a fluctuant abscess and what are the steps?

I&D

1. Anesthetize

2. Incise over point of maximal fluctuance

3. Break loculations

4. Irrigate

5. Consider loop drainage/packing

What is hidradenitis suppurativa?

Chronic inflammatory disease of apocrine gland bearing skin folds.

Lesions: painful nodules, abscesses, interconnected tunnels (sinus tracts), scarring

Flare/medical care: warm compresses, topical/oral antibiotics, intralesional triamcinolone 10-40 mg/mL, biologics for moderate-severe

What are the typical sites of hidradenitis suppurativa?

Axillae

Groin

Inframammary

Perianal

What are the procedures for hidradenitis suppurativa and their recurrence rate?

Acute abscess -> I&D: recurrence 100%, immediate relief but not definitive

Deroofing: low recurrence, remove tunnel roof, heal by secondary intention; high satisfaction, preferred over simple drainage

Wide local excision: lowest recurrence. ≥1 cm margin of healthy skin for interconnected tunnels/plaques; highest morbidity.

How do you manage a seroma/hematoma?

Small/asymptomatic: observe and compress

Symptomatic/enlarging: aspiration or drain

What is the technique for seroma/hematoma management?

Sterile prep, large-bore needle/catheter at most dependent/fluctuant point; compression dressing after

What should be done for recurrent or expanding seroma/hematoma?

Recurrent seroma: repeat aspiration, closed-suction drain, or sclerosis

Expanding hematoma: evaluate for surgical evacuation/bleeding source

How do you classify burns by depth?

1st degree Superficial: epidermis only; red, painful, no blisters; heals without scarring

2nd degree Superficial partial-thickness: into dermis; blisters, moist, painful; heals ≤3 weeks

2nd degree Deep-partial thickness: deeper dermis; may need early tangential excision, refer to burn surgeon

3rd degree Full-thickness: entire dermis; leathery/insensate, refer to burn center.

What is the initial management for burns?

First aid for about first 20 minutes.

Cool, running water (not ice); remove clothing/jewelry; cover with clean/sterile dressing.

When should you refer to a burn center?

1. Partial thickness >10% TBSA

2. Any full-thickness burn

3. Face, hands, feet, genitalia or major joints

4. Inhalation injury; chemical or electrical burns

5. Diabetics/immunocompromised patients.

How do you estimate %TBSA?

Lund-Browder chart.

How do you stage pressure ulcers?

Stage 1: intact skin, non-blanching erythema

Stage 2: partial-thickness loss, exposed dermis (shallow ulcer/blister)

Stage 3: full thickness loss into subcutaneous fat

Stage 4: full thickness loss with exposed muscle/tendon/bone

How do you manage pressure ulcers?

1. Prevention/foundation: pressure redistribution, support surfaces, nutrition (protein/amino acids)

2. Wound care: debridement of necrotic tissue; hydrocolloid > gauze for size reduction; NPWT for stage 3-4

3. Surgery for recalcitrant stage 3-4: debridement and flap reconstruction (+/- ostectomy of bony prominence)

4. Support surfaces: air fluidized beds superior for reducing ulcer size.

Describe the blood supply feature of reconstruction in skin grafts vs flaps

Skin graft: avascular; relies on recipient bed neovascularization

Flap: brings its own vascularity (pedicled or free)

Describe the bed requirement feature of reconstruction in skin grafts vs flaps

Skin graft: needs vascularized bed; fails on bare bone/tendon/irradiated tissue

Flap: can cover avascular/exposed vital structures

Describe the types of reconstruction in skin grafts vs flaps

Skin graft: split thickness vs full thickness

Flap: local/random, regional, pedicled, free

Describe the best use feature of reconstruction in skin grafts vs flaps

Skin graft: large, shallow, well-vascularized defects

Flap: high-tension sites, exposed bone/tendon, poor beds

What is included in the pre-operative evaluation for reconstruction?

1. Testing

2. Meds

3. Staging

4. Tumor conference

5. Consent

6. Prophylaxis

What are the perioperative risks and post-op complications?

1. Bleeding risk

2. Infection risk

3. Local anesthetic planning

4. Common complications: pain, bleeding/hematoma, seroma, infection.